This power control from a 1968 Motorola manual shows how to use a contemporary diac as a zero-crossing detector. The SCR is of the type depending on the power of the load.
In the figure we show how to use a 555 to control an SCR or another type of thyristor. Resistors R1, R2...
This circuit was taken from the 1974 Ferranti transistor manual. Transistors are common types at...
This interesting intercom circuit was obtained from an Argentine publication from the 1970s....